There are a number of techniques disclosed in the art for locating process tubes within high temperature boilers. Illustrative of such techniques are those disclosed in U.S. Pat. Nos. 3,385,271; 3,552,362 and 4,244,606. In actual practice, however, it is most common to have the process tubes which are located in boilers suspended by tube supports from a superstructure external the boiler roof casing. Thus, the process tubes located in the boiler have upper portions which extend through the boiler roof casing, form a bend, and return back down through the boiler roof casing. The tubes are suspended by tube supports attached to the bend of the tube and superstructure over the roof casing. Experience has shown that these precautions are necessary to avoid mechanical failure of the tube supports which would occur if the supports were located within the boiler where temperatures are generally above at least 1000.degree. F. and often are as high as about 2000.degree. F. and a corrosive atmosphere exists.
There are a number of disadvantages to the common tube support technique in practice, not the least of which is the difficulty associated with providing appropriate expansion joints in the region where the process tubes penetrate the casing of the boiler. Thus, there remains a need for a very simple and economical technique for supporting process tubes in a boiler chamber.